Watch for Anaplasmosis

Farm Journal logo

By Grant Dewell, DVM, ISU Beef Extension Veterinarian

Recently we have seen an increased number of cases of Anaplasmosis from submissions to the Iowa State University Veterinary Diagnostic Laboratory (ISU VDL). Although the disease is not enzootic in Iowa, it is observed regularly. Environmental conditions this year may be enhancing the spread of anaplasmosis within the state.

Anaplasmosis is caused by a protaozoan parasite (Anaplasma marginale) that is spread by ticks and biting insects. Additionally, it can be transmitted by needles or surgical equipment. Once the parasite reaches the blood stream it infects red blood cells (RBCs) where they multiply. Anemia results from an erythrophagocytosis of the RBCs. Anemic animals will develop icterus but not hemoglobinuria because RBC destruction occurs from erythrophagocytosis rather than hemolysis.

Clinical Signs

Clinical signs of anaplasmosis are associated with anemia (hematocrit less than 15%). In acute anaplasmosis, cattle will be febrile and anemic with increased heart and respiratory rates. Cattle may also have muscle weakness, inappetence and depression. Mucus membranes will be pale.  Icterus develops several days after onset of symptoms. Peracute anaplasomosis can be seen in highly susceptible animals such as adult purebred animals or high-producing dairy cows. These cattle can succumb to the infection within hours.  Chronic anaplasomosis may follow an acute infection for up to 3 months of poor response. Young animals will show less severe clinical signs, due to a more responsive production of RBCs. Abortions are common in pregnant cattle with acute anaplasmosis. Bulls may show a temporary infertility which could be important in a fall breeding program.


Diagnosis during the acute stage of the disease is usually based on clinical signs, presence of anemia and microscopic examination of a stained blood smear. In cattle, the A. marginale organisms are located on the periphery of the RBC. However, in some acute infections the organism is not visible on a blood smear because all infected cells were removed from circulation and immature erythrocytes are usually not infected. Serology for A. marginale can be useful to aid in diagnosis in these cases.

Necropsy examination of cattle that die from anaplasmosis reveals either pale and anemic or icteric depending on stage of disease. An enlarged spleen and a swollen liver with enlarged gall bladder are also present. Urine will NOT be discolored with hemoglobin.

Submission samples include blood smear or EDTA blood tube sample, Serum sample or clotted blood sample for serology. Tissues to submit include liver, spleen, kidney.


Tetracycline is the drug of choice for clinical anaplasmosis. A single dose of long-acting 200 mg/ml oxytetracycline is usually sufficient. General supportive care is also important for anemic animals. Blood transfusions are of limited benefit. Large volume is needed because of the severe anemia and because the erythrophagocytosis system is activated, transfused RBC are removed from circulation in 24-48 hours.


Typically, cases of anaplasmosis increase in late summer and fall as insect vectors increase. Therefore, control of vectors is key to preventing anaplasmosis. If necessary, herd treatment with oxytetracycline injection every 3 to 4 weeks during high-risk times may be necessary to prevent clinical disease, but animals can become carriers. Another option is oral administration of chlortetracycline at 1.1 mg/kg daily. To remove carrier state, cattle need to treated with long-acting oxytetracycline every 3 days for 4 treatments or 5 mg chlortetracycline per pound body weight orally per day for 30 days.



Latest News

Winter cattle feeding
Cash Cattle Weaker As Grain Rallies

Cash cattle prices slipped lower throughout the week as packer demand was called moderate. Grain markets posted a significant rally on the heels of USDA's report on Tuesday.

2 hours ago
Packing plant workers
Fired Tyson Managers: ‘Betting Pool’ Stories Distorted

Former Tyson Foods Waterloo, Iowa, plant managers dispute claims of how an "office pool" regarding COVID-19 was portrayed in news stories and deny it was about how many employees would contract the virus.

1 hour ago
Dream Lake with Hallett Peak in the background, at Rocky Mountain National Park.
Hi-Plains Researchers To Help Protect Rocky Mountain National Park

A Texas A&M AgriLife team will work with the Colorado Livestock Association and other stakeholders to refine and evaluate practices to reduce agricultural ammonia emissions into Colorado’s Rocky Mountain National Park.

12 min ago
AL Ranch
Beef. It’s What’s For Dinner. Launches “MBA NextGen”

MBA NextGen updates the popular MBA training modules making it easier than ever for a new generation of farmers and ranchers to share their story and advocate knowledgeably for the beef industry.

8 min ago
Greg Henderson
Overall Meat Sales Higher In 2020

Meat sales - both dollar values and volume - were significantly higher in 2020. Those gains, however, came at the expense of a crippled restaurant and food service industry that may take years to recover.

9 min ago
Progressive Beef
Progressive Beef and Wendy’s® Advance Partnership

Wendy's announces 15% increase in percentage of beef sourced through Progressive Beef-certified producers in 2020; on track to meet goal of at least 50% this year.

14 min ago